Remotely actuated device for surveying underground strata

ABSTRACT

Device for taking cores of the ground formations at different levels of a well, adapted to be operated successively as a drilling apparatus and as a coring apparatus and comprising remotely controlled means for passing from drilling conditions to coring conditions and vice-versa by actuating a retractable plug member of the coring crown of the device by means of a variation of the flushing fluid pressure and/or a rotation of the device.

United States Patent [191 Courtois [451 Sept. 3, 1974 15 REMOTELYACTUATED DEVICE FOR 2,343,805 3/1944 Sewell 175/233 SURVEYINGUNDERGROUND STRATA 2,708,103 5/1955 Wi11iams.. [75/330 X 3,283,83511/1966 Kellner 175/317 Inventor: Lucien Courtois, Paris. France3,323,604 6/1967 Henderson 175 58 x 3 548 958 12/1970 Blackwell et a1.175/242 X [73] Assignee: Institut Francais du Petrole, des

Carburants at Lubrifiants, 3,700,049 10/1972 Tiraspolsky et a1 175/404 XRueil-Malmaison, France [22] Filed; 13, 1972 Primary Examiner-David H.Brown Attorney, Agent, or FirmCraig & Antonelli [21] Appl. No.: 314,527

[30] Foreign Application Priority Data [57] ABSTRACT Dec. 17, 1971France 71.45655 Device for taking cores of the ground formations at [52]US. Cl 175/87, 175/238, 175/242, diff t l v ls of a well, adapted to beoperat d 175/317 175/330- cessively as a drilling apparatus and as acoring appa- 1 Cl 1 1321b 25/00, E2113 9/36 ratus andcomprising remotelycontrolled means for Field of Search 175/58, 60, 233, passing fromdrilling conditions to coring conditions 175/238242, 248, 871 andvice-versa by actuating a retractable plug member 1 1:115933291.320L28li94lfi6 of the coring crown of the device by means ofa variation of the flushing fluid pressure and/or a rotation of [56]References Cited the device UNITED STATES PATENTS 2,238,609 4/1941Sewell 175/242 X 23 Claims, 10 Drawing Figures PATENTEB SEP 3 7 sum -01%10 PATENIEDsEP 3:914 3,833,074

sum 02 or 10 FIG.Z

PATENTEDsEP 31974 SHEET DR 0F 10 FIG.4

PATENTED BE? 3 I974 SHEET 05 0F 10 PATENTEU W sum as or 10 PATENTEDSEP31914 SHEET1'100F 1o FIGJU REMOTELY ACTUATED DEVICE FOR SURVEYINGUNDERGROUND STRATA The present invention relates to a new remotelyactuated device for surveying underground strata.

In the following reference will be made more particularly, by way ofnon-limitative example only, to a device for collecting ground samplesor cores, suitable, in particular, for underwater coring, for surveyingpurposes.

One of the most serious difficuities encounteredin the course of suchoperation, is the need to carry out in successively order drilling andcoring operations for taking a core at a depth exceeding the usefullength of the coring device, with in addition some risks of the boreholewalls crumbling during the interval between said successive drilling andcoring operations. Such crumbling due to drilling through unconsolidatedformations makes difficult or impossible the identification of the corestaken subsequently.

The specification of the French Pat. .No. 1,563,642, filed on Mar. 9,1967, describes a remotely actuating coring device, enabling fulldiameter drilling of a bore, like a conventional drill tool, up to thedepth selected for taking a ground sample, this device being thentransformable into a coring tool, by remote control performed from theground surface, once this depth has been reached.

A drawback of this prior device lies in the fact that only one samplecan be taken. Thus, if a plurality of cores must be taken, correspondingto different depths, it is necessary, after the first coring operationhas been achieved, to raise the device out of the borehole, then extractthe core from this device and reset-the device into its drillingposition before lowering it again into the borehole.

This last operation requires the use of means for guiding the device sothat it can be reintroduced into the borehole. During underwatersurveying operations it is not always possible to install such guidingmeans and if a plurality of ground samples or cores must be taken atvery different depths, it becomes then necessary to perform a number ofdrilling operations equal to the number of cores to be taken, whichincreases the duration and consequently the cost of the entire forunderwater surveying operation.

The main object of the present invention is accordingly to provide acoring device capable of taking, successively, a plurality of groundsamples or cores, at different depths, these cores being obtained bydrilling a single bore, without requiring the raising of the coringdevice from the bore and its reintroduction thereinto after each groundsample has been taken.

In other words, the invention provides a device capable in the course'ofsingle run to drill at full diameter up to a first selected depth, totake a first core exclusively when said first selected depth has beenreached,

then to drill again at full diameter in a single drilling runv up to asecond selected-depth, to take a second core exclusively at said seconddepth and so on for any number of cores to be taken.

The device according to the invention comprises a tubular body which isprovided with a coring crown at its lower end, means for making saidtubular body fast in rotation with driving means and for connecting saidbody with a source of flushing fluid under pressure, means for surveyingthe ground layers, said surveying means being housed within said tubularbody, a plug having a first position corresponding to drilling, whereinsaid plug prevents the building of a core in the central part of saidcoring crown, and a second position corresponding to surveyingoperations performed in the ground layers, wherein said plug is removedfrom the central part of said coring crown and actuating means forcontrolling the position of said plug.

In the device according to the invention, said actuating means areconstituted by means for reversibly displacing said plug from said firstto said second position, by means of a control device for said plug,said control device being axially displaceable along and rotatablymounted on guiding means, said actuating means being adapted to displacesaid plug from said first to said second position under the action of atleast one pressure variation in the flushing fluid and to displace itfrom said second to said first position under the action of at least arotation of said device, following a stopping of this device, saidrotation being itself followed by at least one variation in the pressureof the flushing fluid.

The invention will be more fully understood and other advantages thereofwill be made apparent in the following description of a non-limitativeembodiment thereof, illustrated by the accompanying drawings wherein:

FIG. 1 is a diagrammatic sectional view of a device according to theinvention;

FIG. 2 is a developed view of the guiding ring; FIGS. 3 to 10 illustratethe operation of the device according to the invention.

FIG. 1 is a diagrammatically sectional view of the coring deviceaccording to the invention, ready to drill at full diameter.

This device comprises a tubular body 1 of substantial length, formed ofa plurality of tubular elements connected end to end through anysuitable means. At its upper end the body 1 is extended by an element 2for connection to means (not shown) for driving the device in rotationand connecting this device to a source of flushing fluid under pressure.The device may in particular be connected to the lower end of a drillpipe. A crown-shaped drill bit 3 is secured at the lower end of the body1.

During the core sampling operations, a core is formed in the centralpart of the crown bit 3.

In order to permit full diameter or full bore drilling, there isprovided a plug indicated as a whole by reference numeral 4. V

The plug 4, located substantially on the axis of the device and in theclose vicinity of the drill bit, mainly comprises a substantiallyspherical ball 5. This ball is integral with a shaft 6 whose axis passesthrough the center of the ball 5. The shaft 6 journaled on bearingsprovided in the wall of the body 1 is perpendicular to the vertical axisof the device. The shaft 6 is provided,

on both sides of the ball 5, with a toothed conical pinion (pinions7 and8 respectively). The pinion 7 is integral with the shaft 6 and thepinion 8 is idle on this The external wall of the ball 5 is providedwith cutting elements, constituted for example by a diamond concretion,which, for certain positions of the ball 5 permits the destruction ofthe core which would otherwise be formed in the central bore of thecrown bit 3.

At the upper end of and inside the body 1, is secured a guiding ring thewall of which is provided with a slot or guide path 11 having the shapeillustrated by FIG. 2, which is a developed view of the guiding ring 10.

The guiding ring 10 is extended at its lower end by a discharge ring 12,integral with the body 1. The diameter of the bore of ring 10 may beidentical to or greater than that of ring 12. The ring 12 and theinternal wall of the body 1 define an annular space 13 which, on the onehand, communicates at its lower part, with the in-- ternal bore of thebody 1 through vertical ducts 14 and, on the other hand, communicates atits upper part with the internal bore of the ring 12 through fouropenings 15 located at one and the same first level and regularlydistributed, i.e., at a interval of 90.

The internal wall of the ring 12 is provided below the openings 15 withan annular slot 16, whose object is explained more fully hereinafter.

A cylindrical distributor 17 is slidably and rotatably mounted in thebore of the ring 12.

The upper part of the distributor 17 is provided with a bore 18 whosewall is provided on its upper face with locking teeth 19.

Eight openings 20 located at one and the same level and regularlydistributed, i.e. at an angular interval of 45 from each other, areprovided through the wall of the distributor 17, opening out in the bore18. Eight openings 21 are provided at a second level below said firstlevel and offset by 2230 with respect to the openings 20, these orifices21 opening in the bore 18.

A piston 22 is placed along the axis of the device. 1

This piston 22 has an upper part 23 of greater diameter which may slide.within the bore of the guiding ring 10, and a lower part 24 of smallerdiameter which may slide in the bore 18 of the distributor 17.

The upper part 23 of the piston 22 is provided with two lugs or guidingfingers 25 and 25', only one of which is shown in FIG. 1 and whichcooperate with the slot 11 of the guiding ring 10 for determining themovements of piston 22. The part 23 of piston 22 is provided withlocking teeth 26 which can cooperate with-the teeth 19 of distributor17.

At a first level of the lower part 24 of piston 22, four openings 27,regularly distributed, communicate with vertical ducts 28 of piston 22opening into the upper face of this piston. At a second level of thepart 24 four openings 29 regularly distributed at an angular interval of45 with respect to the openings 27, communicate with the ducts 28.

Flap valves 30 provide for a selective communication between the ducts28 and the openings 27 and 29.

A spring 31 is placed between the piston 22 and the distributor 17.

The distributor 17 is integral with an extension member 32 constitutedby a tubular element whose lower end is provided on its outer surfacewith grooves 33 parallel to the axis of the device. These groovescooperate with a tubular element 34 provided with complementary grooves35.

The tubular element 34 is provided with a toothed crown 36 which is inmesh with pinions 7 and 8 provided on the shaft 6.

The tubular element 34 is held in position by bearings 37 integral withthe body 1 with respect to which this tubular element 34 is rotatable.

The element 34 thus constitutes a telescopic coupling between thepinions 7 and 8 and the extension member 32 which is axiallydisplaceable.

The extension member 32 is held in position within the bore of the body1 by bearings (not shown) and a spring 38 located between a shoulder 39integral with the body 1 and a shoulder 40 integral with the extensionmember 32.

Other elements such as the stops 41 and 42 carried by the body 1 of thedevice and the extension member 32 respectively, limit the axialmovements of the extension member 32.

Cotter pins 43 are housed in radial slots 44 provided in the distributor17 below the bore 18.

Within the extension member 32 is housed a core barrel 45 constituted,for example, by a plurality of elements connected end to end.

The core barrel 45 is held in the extension member 32 through bearings46, such as ball bearings, allowing a relative rotation of the extensionmember and the core barrel.

At its upper end, the bore of the core barrel 45 communicates with theinternal bore of the tubular body 1 through a non-return flap valve 47and ducts 48.

The flap valve 47 only permits a fluid flow from the core barrel 45towards the bore of the body 1.

The core barrel is provided with conventional devices, called catchers,well known to those skilled in the art, to hold in place the samples orcores.

As its lower end, the core barrel 45 has an outer diameter slightlysmaller than the diameter of the bore 9 of the plug 4.

An actuation rod 49, which passes through the piston 22 and between thepins 43, penetrates at its end into a recess 50 provided in thedistributor 17.

The rod 49 is provided at its lower part with a conical shoulder 51connecting this rod 49 to cylindrical part 52 of greater diameter.

At its upper end, the rod 49 is integral with a piston 53 which isdisplaceable in a cylindrical recess 54 provided in a support member 55integral with the body 1. The rod 49 and the piston 53 are supported bya spring 56 provided between the piston 53 and the supportmember 55, sothat, at rest, thepiston 53 be in its uppermost position.

The cylindrical space 54 is obturated at its upper end by a shutter 57connected to a small mass 58 which, under the action of the centrifugalforce, can rotate about a shaft 59 integral with the support member 55.

Ducts 60 are provided through the support member 9 55, for the passageof the flushing-fluid therethrough.

FIG. 2 illustrates in a developed view the slot or guide path 11provided in the ring 10.

This slot comprises vertical parts 0 1-1 L K O, I-I' L,.I',, O I-I L K OH' and L J provided on generatrices regularly spaced on the ring 10,i.e. limiting eight ring portions corresponding to arcs of a circle of45. I

These vertical parts are interconnected through identical inclined partsof the slot H,J,, H,.I',, H 1 and H J' The points 0,, 0' 0 and O, arelocated at one and the same first level, the points H,, L,, H,, L',, H LH, and L' being located at a second level, below said first level. Thepoints 1,, J,, J, and J' are located at one and the same third level,below said first and second levels, while the points K, and K arelocated at a fourth level below the preceding ones.

The operation of the device will be indicated hereinunder with referenceto the drawings.

During the drilling operation, the plug 4, the piston 22 and thedistributor 17 are in the position illustrated by FIG. 1, i.e., the boreof the crown bit 3 is obturated by the ball 5. The centrifugal forceresulting from the rotation of the device during a drilling operationcauses the valve 30 to assume a position closing the opening 27 wherebyonly the openings 29, 21 and of the piston 22 and of the distributor 17of the discharge ring 12 register with one another so as to allow theflow of drilling fluid.

When after a drilling operation at full diameter the device reaches thedepth at which a coring operation has to be carried out, the rotation ofthe device is stopped, as well as itsfeeding with flushing fluid and theflap valve 30 assumes the position illustrated in FIG. 1.

The device is then in its position illustrated by FIG. 1, the flapvalves 30 interrupting any communication between the ducts 28 and theopenings 29. The lugs 25 and 25' are respectively located at points 0and 0 (FIG. 2) on the guide path 11.

For sake of clarity, reference will only'be made hereinafter to thedisplacement of the lug 25 along the guide slot 11, the number of lugsbeing obviously non limitative, provided that the guide slot comprisesat least as many times a part such as O H,K L1O' H,J'1L,O as therearelugs integral with the piston 22,

Flushing fluid under a pressure P is then supplied to the device. Thepressure acts on the upper face of piston 22 which moves downwardly andvertically guided by the lug 25 which is displaced in the slot 11 untilpoint H, (FIG. 2).

In this position the spring 31 is compressed and the teeth 19 and 26cooperate so as to make fast in rotation the piston 22 and thedistributor 17 (FIG. 3).

By increasing the pressure up to a value P greater than P,, thedisplacement of the piston is continued. The lug 25 is moved along thepart H of the slot (FIG. 2), thus producing'a determined rotation of thepiston 22 together with a downward displacement of this piston.

As indicated hereinabove, since the piston 22 and the distributor 17 areconnected to each other, this displacement is also imparted to thedistributor 17, thus causing a downward displacement and a rotation ofthe extension member 32 while partly compressing the spring 38. Thisdisplacement has two effects:

a. The rotation of the extension member 32 results, through the grooves33-35, in the rotation of the element 34 and of the crown 36.

The number of teeth of the crown 36 and of the pinion 7 has been sodetermined that the ball 5, under the action of this rotation, rotatesby 90 about its shaft 6, so that the axis of the bore 9 comes intoregistration with the axis of the device, thus making free the bore ofthe tool 3.

b. The vertical displacement of the piston 22 brings closer to eachother the lower end of the core barrel 45 and the plug 4. I

The device is then in the position illustrated by FIG. 4, without anycommunication between the openings 15, 21, 29, 20 and 27.

By increasing the pressure up to a value P greater than P the lug 25 isdisplaced along the part 1 K, of the slot (FIG. 2) and the downwarddisplacement of the assembly is continued without rotation. The lowerend of the core-barrel penetrates into the bore 9 of the ball. When thelug 25 reaches the point K, of the guide slot 11, the pins 43 registerwith the slot 16 whereinto they are urged by the conical abutment 51, onwhich they bear. The lower end of the core barrel which has penetratedthe bore 9 of the ball 5 is located in the vicinity of the working faceof the crown bit 3, as shown in FIG. 5. The distributor 17 is locked inthis position by the pins 43. In this position only the openings 20communicate with the openings 15 of the discharge ring 12.

The flow of flushing fluid is then interrupted. Under the action of thespring 31, the piston 22 rises back, the lug 25 being displaced alongthe part I(,M (FIG. 2) of the slot. In, this position, which is thecoring position, the openings 27 of the piston communicate with theupper openings 20 of the distributor 17 and the openings 15 of thedischarge ring 12.

A flushing fluid is then circulated which maintains the flap valves 30in the illustrated position and flows along the working face of thedrill bit while following the path indicated by the arrows in FIG. 6. Inorder to carry out a coring operation the device is then driven inrotation. The pressure of the flushing fluid keeps the flap valve 57 inits position wherein it covers the piston 53, thus preventing anydownward displacement of the actuation rod 49 by the flushing fluid.

The core which is formed within the bore of the crown bit 3 penetratesthe core barrel 45 in which this core is kept unbroken and is notdestroyed by friction on the internal wall of the core barrel 45 sincethe latter is not driven in rotation by the extension member 32, due tothe presence of ball bearings 46 between these two elements.

When the length of the so-formed core is deemed sufficient and thatanother coring operation is to be carry out at a very different depth,the rotation of the device and then the fluid supply thereto arediscontinued.

The device is then again rotated. Under the action of the centrifugalforce, the weight 58 rotates about its shaft 59, driving the flap valve57 which then uncovers the upper part of the space 54. Under the actionof the centrifugal force, the flap valves 30 obturate the upper openings27 of the piston 22, establishing the communication between the ducts 28and the openings 29 of The pins 43 are no longer held in the slot 16 bythe cylindrical part 52 of the rod 49 and, under the action of thespring 38, the assembly rises again, without rotating, guided by the pin25 which is displaced in the slot 11 from point M, to point L (FIG. 2).The device is then in the position illustrated by FIG. 7,i.e., the corebarrel 45 is in its upper position uncovering the bore of the ball ofthe plug 40.

The circulation of flushing fluid is then discontinued. The actuationrod 49 comes back to its initial position and, under the action of thespring 31, the piston 22 moves upwardly thereby releasing from eachother the teeth 19 and 26 which connect the distributor 17 and thepiston 22.

Guided through the pin 25, which is displaced in the slot 11 frompoint 1. to point O',, the piston alone is subjected to a rotationduring its upward movement. The device thus reaches the positionillustrated by FIG. 8, the plug 4 still leaving free the central bore ofthe crown bit 3. v

The flushing fluid is again circulated until its pressure reaches thevalue P, for which the piston 22, guided by the pin 25 displaced from Oto H (FIG. 2), moves downwardly and vertically while the teeth 19 and 26engage each other, thus making the piston 22 fast in rotation with thedistributor 17. When the pressure is increased up to the value P the pin25 is displaced from l-I to J (FIG. 2), thus producing, together with adownward displacement, a rotation of the piston 22, transmitted to thedistributor 17, to the extension member 32, to the tubular element 34and to the toothed crown 36, which, being in mesh with the piston 7,rotates the ball 5 by 90, thus obturating the central bore of the drillbit (FIG. 9).

By decreasing the pressure to the value P the pin 25 is displaced from Jto L,, thus producing an upward movement of the assembly constituted bythe distributor 17 and the extension member.

Upon releasing the pressure and under the combined action of the spring31 and the pin 25 displaced from L to 0 the piston 22 is moved backupwardly and rotates alone, in the position illustrated by FIG. 10,i.e., in the position wherein the openings 29, 21 and communicate.

The device is then back in its drilling position. The drilling operationmay then be performed. For this purpose, the device is rotated, the flapvalves 30 establishing the communication between the ducts 28 and theopenings 29. The flushing fluid is then circulated so as to wash theworking face of the drill bit, through the ducts 60, 28, the openings29, 21 and 15 which register with each other, the annular space 13 andthe bore of the body 1, as indicated by the arrows in FIG. 10.

The part o,i l,r ,L,o',H',J',L",o of the guide slot is identical to thepart O H,K L,O',I-I J L' O followed by the pin 25 during the precedingoperative steps and the same operations may be repeated so as tosuccessively perform a coring operation, a drilling operation, thenagain a coring operation etc Of course the length of the core barrelwill be at least equal to the sum of the lengths of the cores to betaken.

The flap valve 47 and the ducts 48 described with ref- The abutmentssuch as 41,42, 39 and 40 provide for the fixation of the uppermost andlowermost positions of the extension member. Their number andarrangement will be chosen by those skilled in the art in accordancewith the size of the device.

In the case where, as a result of a wrong operation, the operator wantsto know the state or position of the device, it is necessary to performsuccessive pressurizations of the flushing fluid, while this device isnot driven in rotation, until a normal circulation of the flushing fluidis obtained. When a circulation of flushing fluid is obtained while thedevice is not rotated, this means that the device is in its coringposition.

Modifications can be made without departing from the scope of thepresent invention.

It will, for example, be possible to change the number of openingsthrough the different elements provided they can register with oneanother, as indicated hereinabove, during the operation of the device.

It will also be possible to select the value of the angle of rotation ofthe piston 22 for which the device passes from its coring position toits drilling position and viceversa.

The shape of the plug can be modified. It will for example be possibleto substitute for the spherical ball 5 a cylindrical element having abore perpendicular to the rotation axis of this element.

It will also be possible within the scope of the present invention tosubstitute for the core barrel a measuring element such as apenetrometer in order to measure the resistance of the ground layers tothe penetration of a metal pin thereinto.

What I claim is:

1. A device for surveying the ground layers, comprising: a tubular body,a crown-shaped drill bit having a substantially central opening thereindisposed at the lower end of said tubular body, a driving mechanism forrotatably driving the device, means for connecting said tubular bodywith said driving mechanism, means for connecting said tubular body to asource of pressurized flushing fluid, means disposed inside said tubularbody for surveying the ground layers including a selectivelydisplaceable plug means for selectively opening and obturating saidcentral opening, said plug means having a first position correspondingto drilling conditions with said plug obturating said central opening toprevent the building of a core therein and a second open positioncorresponding to'surveying conditions, and actuating means forcontrolling the position of said plug means including guiding means, andat least one control means for reversibly displacing said plug meansfrom said first to said second position, said control means beingaxially displaceable and rotatable with respect to said guiding means.

2. A device for surveying the ground formations, comprising: a tubularbody, a crown-shaped drill bit having a substantially central openingtherein disposed at the lower end of said tubular body, a drivingmechanism for rotatably driving the device, means for connecting saidtubular body with said driving mechanism, means for connecting saidtubular body to a source of flushing fluid, means disposed inside saidtubular body for surveying the ground formations, said lastmentionedmeans including a selectively displaceable plug means for selectivelyopening and obturating said central opening, said plug means having afirst position corresponding to drilling conditions with said plug meansobturating said central opening to prevent the building of a coretherein and a second open position corresponding to the surveyingconditions, and actuating means ope'ratively connected with the sourceof flushing fluid and responsive thereto for controlling the position ofsaid plug means, said actuating means including means for reversiblydisplacing said plug means from said first to said second position,control means operatively connected with said last-mentioned means forcontrolling the displacement thereof, and guiding means, said controlmeans being axially displaceable along and rotatably mounted on saidguiding means, said actuating means selectively displacing said plugmeans from said first to said second position in response to at leastone variation of the flushing fluid pressure and displacing said plugmeans from said second to said first position by rotation of saidcontrol means, following a stopping of said control means, said rotationbeing itself followed by at least one variation of the flushing fluidpressure.

3. A device according to claim 1, wherein said plug means includes asubstantially spherical element, a rotatable shaft means for mountingsaid spherical element in close proximity to said crown-shaped drillbit, said shaft being rotatable about a rotation axis substantiallyperpendicular to the axis of said tubular body, said rotation axispassing substantially through the center of said substantially sphericalelement, said central opening including a bore extending perpendicularto said rotation axis, said bore having a diameter at least equal to theinternal diameter of said crown-shaped drill bit, said bore in saidsecond position being coaxial to said tubular body, said sphericalelement being provided with cutting means on an external wall thereoffor destroying the core formed in said central opening when said plugmeans is in said first position.

4. A device according to claim 1, wherein said means for surveying theground formations further includes a core barrel, and wherein said plugmeans in said second position permits the formation of a core withinsaid central opening.

5. A device according to claim 4, wherein means are provided fordisplacably mounting said core barrel within said tubular body between afirst position and a second position, said first position correspondingto the drilling conditions with the lower end of said core barrel spacedfrom said plug means, said position corresponding to the coringconditions with said core barrel displaced toward said plug means.

6. A device according to claim 5, wherein said plug means includes asubstantially spherical element including an internal bore, and whereinsaid core barrel includes an internal bore, said last-mentioned bore insaid second position of said core barrel being in close extension ofsaid bore of said spherical element.

7. A device according to claim 5, wherein said plug means includes asubstantially spherical element having an internal bore, and whereinsaid last-mentioned bore has a diameter at least equal to the externaldiameter of the lower portion of said core barrel, the lower end of saidcore barrel in said second position thereof penetrating said bore ofsaid substantially spherical element and coming to a position in closeproximity to said cen tral opening.

8. A device according to claim 5, wherein said means for displaceablymounting said core barrel includes resilient means for suspending saidcore barrel inside said connecting means includes longitudinal groovesprotubular body, and wherein means for locking said core barrel in acoring position are provided, said locking means being releasable bychanging the rotational speed of the device and subsequently modifyingthe pressure of the flushing fluid.

9. A device according to claim 8, wherein at least one radial slot andan annular groove are provided, one of said slot and said annular groovebeing carried on said tubular body and the other being solid with saidcorebarrel, and wherein said means for locking said corebarrel in coringposition includes at least one cotter-pin disposed in said radial slot.

10. A device according to claim 9, further comprising means fordisplacing said cotter-pin in said groove when said core barrel is incoring position.

11. A device according to claim 10, wherein a control rod is providedand wherein said means for displacing said cotter-pin includes a conicalshoulder provided on said control rod.

'12. A device' according to claim 11, wherein a piston is provided, saidcontrol rod being solid with said piston, and wherein resilient meansfor suspending said piston is provided interposed between said tubularbody and said piston, said piston being displaceable by the action ofthe flushing fluid pressure to release said core-barrel from its coringposition.

13. A device according to claim 12, further comprising an articulatedshutter for protecting said piston against the action of the fluidpressure when the flushing fluid is circulated and before the rotationof the device.

14. A device according to claim 13, wherein a small" mass solid withsaid shutter is provided for driving said shutter about its articulationaxis as a result of the centrifugal force generated by the rotation ofthe device preceeding the pressurization of the flushing fluid.

15. A device according to claim 5, further comprising remotelycontrolled means for imparting to said corebarrel successive axialdisplacements and rotations relative to said tubualr body.

16. A device according to claim 15, wherein said means for actuatingsaid plug means includes at least one toothed conical pinion provided onsaid rotatably mounted shaft, a toothed crown cooperating with said Ipinion for driving said shaft in rotation, a tubular elebarrel to permitselective rotation of said tubular element therewith.

17. A device according to claim 16, wherein said vided on said corebarrel and longitudianl corrugations provided on said tubular element,said grooves and said corrugations being disposed substantially parallelto the axis of said tubular body.

18. A device according to claim 16, wherein said remotely controlledmeans includes a discharge ring having an internal bore solid with saidtubular body, said discharge ring defining with the bore of said tubularbody an annular space, duct means provided at the upper part of saiddischarge ring for selectively communicating said annular space with theinternal bore of said tubular body, and at least one orifice arrangedthrough the wall of said discharge ring at the upper portion thereof forselectively communicating said annular space with the internal bore ofsaid discharge ring, a distributor member having a bore therein solidwith said core barrel, means for displaceably mounting said member inthe bore of said discharge ring, at least one bore provided at the upperportion of said distributor member along the axis of the device, saidlastmentioned bore including a wall having at a first level at least onefirst orifice communicating with said annular space in the position ofdrilling condition, at least one second orifice at a second level abovesaid first level and shifted with respect to the first orifice forcommunicating said bore with said annular space in the position ofcoring condition, and wherein said control means includes a controlpiston displaceable in said bore of said distributor member, said pistonincluding a lateral wall, at least one first orifice provided in saidlateral wall at a first level, at least one second orifice provided insaid lateral wall shifted with respect to the first orifice in saidlateral wall and at a second level with respect thereto, a duct arrangedin the body of said control piston and opening into the upper facethereof, and wherein said remotely controlled means includes a remotelycontrolled member for selectively establishing communication exclusivelybetween said duct and said first or second orifice of said controlpiston, said duct of said control piston, said first orifice of saidcontrol piston and said orifice of the discharge ring beingsimultaneously in communication only in the position of drillingcondition, said duct of the control piston, said second orifice of thecontrol piston and said orifice of the discharge ring beingsimultaneously in communication only in the position of coringcondition, resilient means interposed between said control piston andsaid distributor member, means for sequentially connecting in rotationsaid control piston to said distributor member and wherein said guidingmeans includes a member for guiding said control piston.

19. A device according to claim 18, wherein said remotely controlledmember includes a flap valve means for establishing a communicationexclusively between said duct of said control piston and said firstorifice of said control piston, said flap valve means being displaceablefrom a first position to a second position by the effect of thecentrifugal force resulting from the rotation of the device occurringbefore the increase in pressure of the flushing fluid.

20. A device according to claim 12, wherein said sequentially connectingmeans includes teeth carried by said control piston and said distributormember, said teeth selectively meshing with one another when, under theaction of the flushing fluid pressure, said piston moves to a positioncloser to said distributor member against the bias of said resilientmeans interposed between said piston and said distributor member.

21. A device according to claim 18, wherein said guiding member includesa closed guiding path, at least one guiding finger displaceable alongsaid guiding path, at least one of said guiding finger and said guidingpath being solid with said tubular body and the other being solid withsaid control piston.

22. A device according to claim 21, wherein said guiding member consistsof a guiding ring solid with said tubular member and disposed in thebore thereof, said guiding ring including a slot defining said guidingpath, said guiding finger being solid with said control piston, andwherein a resilient means is interposed between said tubular body andsaid core barrel, said slot being formed of successive portions withsaid guiding finger being guided therealong by predetermined variationsin the pressure of the flushing fluid, said successive portionsincluding at least:

a first portion imparting to said control piston, when the flushingfluid pressure is increased up to a first value, a vertical displacementfrom a first value corresponding to drilling conditions of the device,to a second level below said first level with said control piston beingconnected with said distributor member through said connecting means,second portion imparting to said control piston, when the flushing fluidpressure is increased up to a second value greater than said firstvalue, a rotational movement with a simultaneous vertical displacementfrom said second level to a third level below said second level saidrotational movement and said vertical movement being imparted throughsaid means connecting said core barrel to said distributor member, therotational movement being imparted through said actuating means to saidspherical element to rotate the same by about its axis to a positioncorresponding to coring conditions;

a third portion imparting to said control piston a vertical movementfrom said third level to a fourth level below said third level when theflushing fluid pressure is increased from said second value to a thirdvalue greater than said second value, and a vertical movement from saidfourth level to said second level, when the flushing fluid pressure isreduced from said third value to said first value under the action ofsaid resilient means interposed between said tubular body and said corebarrel;

a fourth portion imparting to said control piston, in the absence of aflushing fluid pressure and by the action of said resilient meansinterposed between said piston and said distributor member, a rotationaltogether with a vertical displacement from said second level to saidfirst level;

a sixth portion imparting to said control piston, when the flushingfluid pressure is increased up to said second value, a rotationalmovement together with a vertical displacement from said second level tosaid third level, said rotational movement being imparted through saidconnecting means by said dis- .tributor member and said actuating meansto said spherical element to rotate the same by 90 about its axis to aposition of drilling conditions;

a seventh portion imparting to said control piston, when the flushingfluid pressure is decreased from said second value to said first valueand by the action of said resilient means interposed between saidtubular body and said core-barrel, a vertical dis placement from saidthird level to said secon level; and

an eighth portion imparting to said control piston, in the absence of aflushing fluid pressure and by the action of said resilient meansinterposed between said piston and said distributor member, a rotationalmovement together with a vertical displacement from said second level tosaid first level whereby the device is placed in the drilling condition.

23. A device according to claim 21, wherein a tubular extension memberis provided, and wherein said core-barrel is disposed in said tubularextension member, and wherein bearing means are provided for fixing saidtubular extension member to said distributormemher and for permittingthe relative rotation 'of the corebarrel with respect to said extensionmember.

' I)! I I

1. A device for surveying the ground layers, comprising: a tubular body,a crown-shaped drill bit having a substantially central opening thereindisposed at the lower end of said tubular body, a driving mechanism forrotatably driving the device, means for connecting said tubular bodywith said driving mechanism, means for connecting said tubular body to asource of pressurized flushing fluid, means disposed inside said tubularbody for surveying the ground layers including a selectivelydisplaceable plug means for selectively opening and obturating saidcentral opening, said plug means having a first position correspondingto drilling conditions with said plug obturating said central opening toprevent the building of a core therein and a second open positioncorresponding to surveying conditions, and actuating means forcontrolling the position of said plug means including guiding means, andat least one control means for reversibly displacing said plug meansfrom said first to said second position, said control means beingaxially displaceable and rotatable with respect to said guiding means.2. A device for surveying the ground formations, comprising: a tubularbody, a crown-shaped drill bit having a substantially central openingtherein disposed at the lower end of said tubular body, a drivingmechanism for rotatably driving the device, means for connecting saidtubular body with said driving mechanism, means for connecting saidtubular body to a source of flushing fluid, means disposed inside saidtubular body for surveying the ground formations, said last-mentionedmeans including a selectively displaceable plug means for selectivelyopening and obturating said central opening, said plug means having afirst position corresponding to drilling conditions with said plug meansobturating said central opening to prevent the building of a coretherein and a second open position corresponding to the surveyingconditions, and actuating means operatively connected with the source offlushing fluid and responsive thereto for controlling the position ofsaid plug means, said actuating means including means for reversiblydisplacing said plug means from said first to said second position,control means operatively connected with said last-mentioned means forcontrolling the displacement thereof, and guiding means, said controlmeans being axially displaceable along and rotatably mounted on saidguiding means, said actuating means selectively displacing said plugmeans from said first to said second position in response to at leastone variation of the flushing fluid pressure and displacing said plugmeans from said second to said first position by rotation of saidcontrol means, following a stopping of said control means, said rotationbeing itself followed by at least one variation of the flushing fluidpressure.
 3. A device according to claim 1, wherein said plug meansincludes a substantially spherical element, a rotatable shaft means formounting said spherical element in close proximity to said crown-shapeddrill bit, said shaft being rotatable about a rotation axissubstantially perpendicular to the axis of said tubular body, saidrotation axis passing substantially through the center of saidsubstantially spherical element, said central opening including a boreextending perpendicular to said rotation axis, said bore having adiameter at least equal to the internal diameter of said crown-shapeddrill bit, said bore in said second position being coaxial to saidtubular body, said spherical element being provided with cutting meanson an external wall thereof for destroying the core formed in saidcentral opening when said plug means is in said first position.
 4. Adevice according to claim 1, wherein said means for surveying the groundformations further includes a core barrel, and wherein said plug meansin said second position permits the formation of a core within saidcentral opening.
 5. A device according to claim 4, wherein means areprovided for displacably mounting said core barrel within said tubularbody between a first position and a second position, said first positioncorresponding to the drilling conditions with the lower end of said corebarrel spaced from said plug means, said position corresponding to thecoring conditions with said core barrel displaced toward said plugmeans.
 6. A device according to claim 5, wherein said plug meansincludes a substantially spherical element including an internal bore,and wherein said core barrel includes an internal bore, saidlast-mentioned bore in said second position of said core barrel being inclose extension of said bore of said spherical element.
 7. A deviceaccording to claim 5, wherein said plug means includes a substantiallyspherical element having an internal bore, and wherein saidlast-mentioned bore has a diameter at least equal to the externaldiameter of the lower portion of said core barrel, the lower end of saidcore barrel in said second position thereof penetrating said bore ofsaid substantially spherical element and coming to a position in closeproximity to said central opening.
 8. A device according to claim 5,wherein said means for displaceably mounting said core barrel includesresilient means for suspending said core barrel inside said tubularbody, and wherein means for locking said core barrel in a coringposition are provided, said locking means being releasable by changingthe rotational speed of the device and subsequently modifying thepressure of the flushing fluid.
 9. A device according to claim 8,wherein at least one radial slot and an annular groove are provided, oneof said slot and said annular groove being carried on said tubular bodyand the other being solid with said core-barrel, and wherein said meansfor locking said core-barrel in coring position includes at least onecotter-pin disposed in said radial slot.
 10. A device according to claim9, further comprising means for displacing said cotter-pin in saidgroove when said core barrel is in coring position.
 11. A deviceaccording to claim 10, wherein a control rod is provided and whereinsaid means for displacing said cotter-pin includes a conical shoulderprovided on said control rod.
 12. A device according to claim 11,wherein a piston is provided, said control rod being solid with saidpiston, and wherein resilient means for suspending said piston isprovided interposed between said tubular body and said piston, saidpiston being displaceable by the action of the flushing fluid pressureto release said core-barrel from its coring position.
 13. A deviceaccording to claim 12, further comprising an articulated shutter forprotecting said piston against the action of the fluid pressure when theflushing fluid is circulated and before the rotation of the device. 14.A device according to claim 13, wherein a small mass solid with saidshutter is provided for driving said shutter about its articulation axisas a result of the centrifugal force generated by the rotation of thedevice preceeding the pressurization of the flushing fluid.
 15. A deviceaccording to claim 5, further comprising remotely controlled means forimparting to said core-barrel successive axial displacements androtations relative to said tubualr body.
 16. A device according to claim15, wherein said means for actuating said plug means includes at leastone toothed conical pinion provided on said rotatably mounted shaft, atoothed crown cooperating with said pinion for driving said shaft inrotation, a tubular element solid with said crown, said tubular elementbeing disposed inside of and coaxial with said tubular body with respectto which it is rotatable, and means for selectively connecting saidtubular element with said core barrel to permit selective rotation ofsaid tubular element therewith.
 17. A device according to claim 16,wherein said connecting means includes longitudinal grooves provided onsaid core barrel and longitudianl corrugations provided on said tubularelement, said grooves and said corrugations being disposed substantiallyparallel to the axis of said tubular body.
 18. A device according toclaim 16, wherein said remotely controlled means includes a dischargering having an internal bore solid with said tubular body, saiddischarge ring defining with the bore of said tubular body an annularspace, duct means provided at the upper part of said discharge ring forselectively communicating said annular space with the internal bore ofsaid tubular body, and at least one orifice arranged through the wall ofsaid discharge ring at the upper portion thereof for selectivelycommunicating said annular space with the internal bore of saiddischarge ring, a distributor member having a bore therein solid withsaid core barrel, means for displaceably mounting said member in thebore of said discharge ring, at least one bore provided at the upperportion of said distributor member along the axis of the device, saidlast-mentioned bore including a wall havIng at a first level at leastone first orifice communicating with said annular space in the positionof drilling condition, at least one second orifice at a second levelabove said first level and shifted with respect to the first orifice forcommunicating said bore with said annular space in the position ofcoring condition, and wherein said control means includes a controlpiston displaceable in said bore of said distributor member, said pistonincluding a lateral wall, at least one first orifice provided in saidlateral wall at a first level, at least one second orifice provided insaid lateral wall shifted with respect to the first orifice in saidlateral wall and at a second level with respect thereto, a duct arrangedin the body of said control piston and opening into the upper facethereof, and wherein said remotely controlled means includes a remotelycontrolled member for selectively establishing communication exclusivelybetween said duct and said first or second orifice of said controlpiston, said duct of said control piston, said first orifice of saidcontrol piston and said orifice of the discharge ring beingsimultaneously in communication only in the position of drillingcondition, said duct of the control piston, said second orifice of thecontrol piston and said orifice of the discharge ring beingsimultaneously in communication only in the position of coringcondition, resilient means interposed between said control piston andsaid distributor member, means for sequentially connecting in rotationsaid control piston to said distributor member and wherein said guidingmeans includes a member for guiding said control piston.
 19. A deviceaccording to claim 18, wherein said remotely controlled member includesa flap valve means for establishing a communication exclusively betweensaid duct of said control piston and said first orifice of said controlpiston, said flap valve means being displaceable from a first positionto a second position by the effect of the centrifugal force resultingfrom the rotation of the device occurring before the increase inpressure of the flushing fluid.
 20. A device according to claim 12,wherein said sequentially connecting means includes teeth carried bysaid control piston and said distributor member, said teeth selectivelymeshing with one another when, under the action of the flushing fluidpressure, said piston moves to a position closer to said distributormember against the bias of said resilient means interposed between saidpiston and said distributor member.
 21. A device according to claim 18,wherein said guiding member includes a closed guiding path, at least oneguiding finger displaceable along said guiding path, at least one ofsaid guiding finger and said guiding path being solid with said tubularbody and the other being solid with said control piston.
 22. A deviceaccording to claim 21, wherein said guiding member consists of a guidingring solid with said tubular member and disposed in the bore thereof,said guiding ring including a slot defining said guiding path, saidguiding finger being solid with said control piston, and wherein aresilient means is interposed between said tubular body and said corebarrel, said slot being formed of successive portions with said guidingfinger being guided therealong by predetermined variations in thepressure of the flushing fluid, said successive portions including atleast: a first portion imparting to said control piston, when theflushing fluid pressure is increased up to a first value, a verticaldisplacement from a first value corresponding to drilling conditions ofthe device, to a second level below said first level with said controlpiston being connected with said distributor member through saidconnecting means, a second portion imparting to said control piston,when the flushing fluid pressure is increased up to a second valuegreater than said first value, a rotational movement with a simultaneousvertical displacement from said second level to a third level below saidsecond level said rotational movement and said vertical movement beingimparted through said means connecting said core barrel to saiddistributor member, the rotational movement being imparted through saidactuating means to said spherical element to rotate the same by 90*about its axis to a position corresponding to coring conditions; a thirdportion imparting to said control piston a vertical movement from saidthird level to a fourth level below said third level when the flushingfluid pressure is increased from said second value to a third valuegreater than said second value, and a vertical movement from said fourthlevel to said second level, when the flushing fluid pressure is reducedfrom said third value to said first value under the action of saidresilient means interposed between said tubular body and said corebarrel; a fourth portion imparting to said control piston, in theabsence of a flushing fluid pressure and by the action of said resilientmeans interposed between said piston and said distributor member, arotational together with a vertical displacement from said second levelto said first level; a sixth portion imparting to said control piston,when the flushing fluid pressure is increased up to said second value, arotational movement together with a vertical displacement from saidsecond level to said third level, said rotational movement beingimparted through said connecting means by said distributor member andsaid actuating means to said spherical element to rotate the same by 90*about its axis to a position of drilling conditions; a seventh portionimparting to said control piston, when the flushing fluid pressure isdecreased from said second value to said first value and by the actionof said resilient means interposed between said tubular body and saidcore-barrel, a vertical displacement from said third level to said seconlevel; and an eighth portion imparting to said control piston, in theabsence of a flushing fluid pressure and by the action of said resilientmeans interposed between said piston and said distributor member, arotational movement together with a vertical displacement from saidsecond level to said first level whereby the device is placed in thedrilling condition.
 23. A device according to claim 21, wherein atubular extension member is provided, and wherein said core-barrel isdisposed in said tubular extension member, and wherein bearing means areprovided for fixing said tubular extension member to said distributormember and for permitting the relative rotation of the core-barrel withrespect to said extension member.